The year 2000 saw the American Heart Association (AHA) publish new Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. These guidelines will form the basis of the Advanced Cardiac Life Support (ACLS) courses given in the United States.1 While many will wish to attempt to memorize the various algorithms, the changes in the algorithms are not nearly as interesting as the changes in emphasis present in the new handbook. The new guidelines are presented as the product of an “International Consensus on Science” reflecting significant input from leaders in resuscitation medicine from the Americas, Europe, Australia, Canada, New Zealand, and South Africa. The undeniable fact that many previous recommendations were unsupported by scientific evidence, particularly those concerning the administration of anti-arrhythymic drugs in the setting of a cardiac arrest, has been directly addressed. The new guidelines stress interventions that have little chance of causing irreversible injury. This article will review some of the major changes in the new recommendations, and consider logical future directions.
The approach to airway management has been significantly liberalized in the new ACLS guidelines and algorithms. Endotracheal intubation has been de-emphasized due to what is considered an unacceptably high incidence of incorrectly placed tubes found in several studies. The simplest way to sum up the new recommendations would be to say, “Intubate if you know how.” If your skills are not well-developed and current, it is better to ventilate adequately with a bag and mask, laryngeal mask, or combitube, rather than risk misplacing an endotracheal tube. The laryngeal mask airway and combitube are mentioned frequently and prominently, as less practice is required to maintain an acceptable degree of proficiency in inserting these devices. Once any airway device has been placed, there is new and substantial emphasis on confirmation of correct placement by both physical exam and a secondary device, such as a colorimetric CO2 detector, a quantitative capnometer, capnography, or an esophageal detector device.
Basic Life Support
There are several significant changes recommended regarding basic life support. In an adult arrest, rescuers are instructed to “phone first.” The chest compression rate target is now 100/minute, and the compression:ventilation ratio is 15:2 with an unprotected airway and 5:1 if the airway is secured. Lay rescuers no longer perform a pulse check. Instead they assess responsiveness and proceed with CPR if the patient is unresponsive. This change was made to avoid withholding CPR from a pulseless patient due to an errant (rescuer falsely identifying a carotid pulse as being present) pulse check. These changes are made to give the victim of a cardiac arrest the best chance of survival, which results from quick activation of the EMS system, rapid provision of basic life support, and early defibrillation. The text of the guidelines also states that future Basic and ACLS courses will vary significantly from past practice. Lecture time will be drastically reduced, much of the instruction will be video-based, and there will be more emphasis placed on the acquisition and demonstration of the basic skills necessary for BLS and on the proper use of automatic external defibrillators (AEDs).
The new guidelines contain many changes in drug recommendations. Overall, the evidence supporting the efficacy of anti-arrhythmic drugs in the setting of a cardiac arrest is no better than fair, and amiodarone has the most support. When drugs are considered for shock-refractory V-Fib/V-Tach, amiodarone 300 mg IV is supported by more evidence of efficacy than any other drug. Lidocaine and procainamide are now classified as agents supported by indeterminate evidence for this indication, meaning that there is insufficient evidence to recommend them as effective, and that they should not be administered until more effective treatments (amiodarone) have been tried without success. Bretylium has been removed from ACLS algorithms, as it is no longer available, is less effective than amiodarone, and has more side effects.
Another significant change is the elimination of the recommendation for the routine use of high-dose epinephrine. In a cardiac arrest, epinephrine 1 mg IV every 3-5 minutes is acceptable. Higher doses can be considered, but the practitioner should realize that 8 randomized studies involving more than 9,000 patients have failed to document improved survival to hospital discharge with high dose epinephrine administration. The higher doses may lead to more frequent return of spontaneous circulation, but they are associated with exacerbated post-resuscitation myocardial dysfunction. Incredibly, although epinephrine has been universally used in resuscitation, there is a lack of scientific evidence to support its efficacy at any dose. There is still need for a randomized trial comparing epinephrine at standard dosages to placebo, although the ethical and logistic impediments to such a study might be insurmountable.
The lack of evidence supporting the efficacy of epinephrine, as well as recent evidence from several small trials, has led to a recommendation from the AHA that vasopressin, at a one-time only dose of 40 units intravenously, be considered instead of epinephrine 1 mg IV every 3-5 minutes for patients who have suffered a cardiac arrest. Vasopressin, an antidiuretic hormone, functions as a vasoconstrictor when it is used at supraphysiologic doses such as 40 units. Vasopressin is believed to possess vasoconstrictive properties (which serve to bring peripheral blood volume to the central compartment), without some of the adverse effects of epinephrine. Vasopressin only needs to be given once due to its 10-20 minute half-life. Whether or not the addition of vasopressin to the new guidelines is wise will only be determined by research that looks directly at its efficacy. As there is little strong evidence to support the efficacy of epinephrine, it is difficult to fault the decision to introduce vasopressin as an alternative in the algorithms. However, the European Resuscitation Council’s guidelines for adult advanced life support do not include a recommendation for vasopressin, which suggests that the international consensus on science may not be ironclad.
The new guidelines struggle to simplify the approach to the victim of sudden cardiac arrest, while at the same time they reflect the tremendous advances that have been made in the diagnosis and treatment of acute medical conditions. A good example of effective simplification is the Universal ACLS algorithm, found on page 143 of the guidelines. A rescuer following the algorithm would do BLS if indicated, attach a monitor/defibrillator, check the rhythm, and defibrillate 3 times. Drug administration of any kind does not enter into the picture until after defibrillation has been done 3 times. This approach recognizes that defibrillation has good evidence to support its efficacy, while the evidence for the effectiveness of drugs in cardiac arrest is limited. In particular it appears that when anti-arrhythmic drugs are used in combination, a proarrhythmic effect often occurs, a problem addressed at many points in the guidelines.
An example of extreme complexity can be found in the new tachycardia algorithms (3 of them). All three algorithms contain decision points that depend on the patient’s ejection fraction. While the recommendations are based on evidence, the complexity of the recommendations and the inclusion of a physiologic parameter that is difficult to immediately discern make it hard to believe that the guidelines will be useful to first-responders. The new guidelines also stress that new expert algorithms are being developed for clinical conditions such as asthma, drug overdose, and drowning. With the new evidence-based approach adopted by the AHA, these guidelines will be welcome, but it is likely that the information they contain will be most useful when the victim arrives at a hospital.
Resuscitation medicine appears to be at a crossroads. The efficacy of early BLS followed by early defibrillation is not in doubt. Individual communities must work with the resources they have available to ensure the best EMS network they can afford. To improve the chance of early defibrillation, automatic external defibrillators must be deployed wherever there are concentrations of people (workplaces, stadia, airplanes, and so forth). Engineering improvements have simplified AEDs, and they have proven safe and effective for non-medical individuals to use. To maximally improve public health, recommended cardiac arrest care must be simplified, AEDs should be deployed widely (with employers ensuring that someone is on site who can operate them), and patients who have survived should be rapidly turned over to experts who can then responsibly interpret and follow the algorithms for specific medical conditions. Perhaps the current ACLS course offered to first responders should be changed.
By attempting to impart too much information, ACLS courses may fail in their goal to improve the treatment of victims of cardiac arrest. Future courses should be significantly simplified, and should concentrate on the Universal Algorithm, on ensuring familiarity with the AED, and on confirming the ability of individuals to perform BLS skills. This approach could eliminate the dual “certification” in BLS and ACLS and replace it with a “first responder” course that would concentrate on knowledge and skills that can practically be imparted to individuals with limited medical training. Widespread basic training of “first responders” throughout the population would improve survival more than more intensive instruction of fewer individuals.
Dr. Passannante is Associate Professor of Anesthesiology and Director of Resident Education at the University of North Carolina at Chapel Hill.
- The American Heart Association in Collaboration with the International Liaison Committee on Resuscitation (ILCOR). Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2000;102 (suppl):1-380.
- Takata TS, Page RL, Joglar JA. Automated external defibrillators: technical considerations and clinical promise. Ann Intern Med 2001;135:990-8.
- De Latorre F, Nolan J, Robertson C, Chamberlain D, Baskett P. European resuscitation council guidelines 2000 for adult advanced life support. Resuscitation 2001;48:211-21.